go/pointer/testdata/channels.go

// +build ignore

package main

func incr(x int) int { return x + 1 }

func decr(x int) int { return x - 1 }

var unknown bool // defeat dead-code elimination

func chan1() {
	chA := make(chan func(int) int, 0) // @line c1makeA
	chB := make(chan func(int) int, 0) // @line c1makeB
	chA <- incr
	chB <- decr
	chB <- func(int) int { return 1 }

	print(chA)   // @pointsto makechan@c1makeA:13
	print(<-chA) // @pointsto main.incr

	print(chB)   // @pointsto makechan@c1makeB:13
	print(<-chB) // @pointsto main.decr | func@16.9
}

func chan2() {
	chA := make(chan func(int) int, 0) // @line c2makeA
	chB := make(chan func(int) int, 0) // @line c2makeB
	chA <- incr
	chB <- decr
	chB <- func(int) int { return 1 }

	// Channels flow together.
	// Labelsets remain distinct but elements are merged.
	chAB := chA
	if unknown {
		chAB = chB
	}

	print(chA)   // @pointsto makechan@c2makeA:13
	print(<-chA) // @pointsto main.incr

	print(chB)   // @pointsto makechan@c2makeB:13
	print(<-chB) // @pointsto main.decr | func@30.9

	print(chAB)   // @pointsto makechan@c2makeA:13 | makechan@c2makeB:13
	print(<-chAB) // @pointsto main.incr | main.decr | func@30.9

	(<-chA)(3)
}

// @calls main.chan2 -> main.incr

func chan3() {
	chA := make(chan func(int) int, 0) // @line c3makeA
	chB := make(chan func(int) int, 0) // @line c3makeB
	chA <- incr
	chB <- decr
	chB <- func(int) int { return 1 }
	print(chA)   // @pointsto makechan@c3makeA:13
	print(<-chA) // @pointsto main.incr
	print(chB)   // @pointsto makechan@c3makeB:13
	print(<-chB) // @pointsto main.decr | func@58.9

	(<-chA)(3)
}

// @calls main.chan3 -> main.incr

func chan4() {
	chA := make(chan func(int) int, 0) // @line c4makeA
	chB := make(chan func(int) int, 0) // @line c4makeB

	select {
	case chA <- incr:
	case chB <- decr:
	case a := <-chA:
		print(a) // @pointsto main.incr
	case b := <-chB:
		print(b) // @pointsto main.decr
	default:
		print(chA) // @pointsto makechan@c4makeA:13
		print(chB) // @pointsto makechan@c4makeB:13
	}

	for k := range chA {
		print(k) // @pointsto main.incr
	}
	// Exercise constraint generation (regtest for a crash).
	for _ = range chA {
	}
}

func main() {
	chan1()
	chan2()
	chan3()
	chan4()
}